Outboard Motors......

Outboard Motors......

Postby ozzibod » Thu Apr 15, 2010 9:33 pm

Good evening folks,

I am at the point of replacing my present outboard motor which sits in a cutout in the transom of my Mk 1. It is a 1993 Evinrude "Yachtwin", an extra long shaft model, 2stroke, 8hp and has what seems to be a high thrust propellor.
I have had the motor since I purchased the boat just over 2 years ago and I have noticed that it chews about 4 to 5 litres an hour at about half to 3/4 throttle. This seems somewhat excessive to me, however I am a newbie when it comes to modern outboards having been brought up on British Seagulls!
I am looking to upgrade and would love to get some of your thoughts on 2 strokes versus 4 strokes and what is an ideal power (6hp? 8hp? 10hp?), make for a TopHat, given that I would be looking for something to push me along at about 4.5 to 5 knots economically.

If you have any thoughts or suggestions, I would be most grateful.

Austin
Sintra II
Montagu Bay, Hobart.
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Re: Outboard Motors......

Postby Sombrero » Thu Apr 15, 2010 10:32 pm

Hi, Austin.
When I purchased SOMBRERO it had a 1997 Evinrude long shaft 6hp twin which was doing the job, but I wanted a bit more power. My previous boat, an Endeavour 24 had an 8 hp Honda four stroke mounted in the well which was overkill for the boat and was too heavy to lift in and out and subsequently succumbed to corrosion in the leg. I replaced it with a 5hp single cylinderTohatsu two stroke and when not in use it went into the cabin on a removable bracket beneath the mast step. It was a great motor (bullet proof) and reasonably economical as two strokes go. So, when my wife watched me frantically trying to get the Evinrude to start, we decided to update our mode of power. Naturally, having been happy with the previous Tohatsu I purchased another, This time an 8hp.two cylinder long shaft model. My boat has a guillotine arrangement over the well and the motor lowers by pulleys and conversely is raised clear of the water when not in use. It has a standard propellor, which was the recommendation of the supplier, because he said there is too much load on on the motor if a high thrust prop is used. One thing I did find that I had not anticipated was that I have to turn the motor a bit to fit down through the bottom of the well because of the shape of the cavitation plate. There was a moment of panic here because I had ordered, paid for and taken delivery of the motor when this problem arose. The 8hp drives the boat well, a 9hp would probably drive it better, but I imagine it would use more fuel. For a two stroke the Tohatsu is reasonably economical. I imagine that most of the two stroke manufacturers are fighting in the same market and are very competitive in terms of their product and its price. In the first instance I chose Tohatsu because my boat is moored at Williamstown and the dealer/service centre is also in Williamstown. Good luck with your decision making.
John S. "SOMBRERO"
Sombrero
 
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Re: Outboard Motors......

Postby azzura » Fri Apr 16, 2010 9:27 am

Hi Austin

I totally agree with John . My boat came with a 5hp tohatsu and its was great motor but just didnt have enough power to push the boat against tides and wind at a reasonable speed with any reserve . So I upgraded to a second hand Mercury 8hp 2 cylinder 2 stroke and its much better suited .
When the the Merc gets too tired I will repalce it with the 8hp Tohatsu . They are reliable and lightwieght, cost less to purchase and service and are made by Mercury anyway.

Good Luck


Mark

"Azzura "
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Re: Outboard Motors......

Postby Miker » Fri Apr 16, 2010 2:19 pm

G'day Austin,

Disclaimer - this is from someone who has had their boat exactly one year this week.

Dulcamara's previous owner had a 9hp Johnson 2 stroke in the well, he said it was noisy and smelly and so pensioned it off for an 8hp 4 stroke Tohatsu. The 4 stroke was a little heavier, and it's head rubbed on the inside of the back of the well, so he took it out and put it on the transom on a stainless adjustable bracket. As you see in the pic. Unfortunately it spoils the lines of the boat, but it is easy to use and burns about 1.5 litres an hour on 3/4 throttle, which I believe pushes the boat at hull speed because with 4 in the cockpit we get water through the well into the cockpit floor. This only happens when the boat is going fast with a few people on board, so a more powerful engine may only increase your fuel bill for little or no gain in speed. That is, apart from the really gnarly days when the 8hp is almost out gunned by a 40 knot wind into your teeth....

Image

Anyway, one thing you should consider is putting it over the back with electric start and remote controls in the cockpit, that would be almost perfect for me.

Michael
Michael
"Dulcamara" - MKIII
Careel Bay, Pittwater
"Order of the Tipping Dinghy" 2017
Miker
 
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Re: Outboard Motors......

Postby karl010203 » Fri Apr 16, 2010 6:31 pm

Ours came with a 9.9 honda 4stroke in the well - too bloody heavy to lift in and out and not happy with lines and pulleys previous owner had to achieve this.

Bought a 8hp two stroke yammy - fits in the well fine - a lot lighter - 26kg vs 48! so I can move and store it in cabin without slipping a disc.

It is noisy and in comparision to a 4 stroke poor on fuel... I can't tell you exact fuel usage but did motor about 25nm once on a tank of fuel - about 20ltrs... flat out, so if that was at about 5-6 knots that would work out at about 4lts an hour. Was deaf at the end of it...

I do like the fact the yammy is 100:1 oil mix - not so smoky...
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Re: Outboard Motors......

Postby Sombrero » Fri Apr 16, 2010 11:14 pm

Hi all outboarders.
I am afraid I am not a fan of outboards hanging out on the stern. They can be a target for thieves (you might as well leave a shifter and the hand book and spares). They do not work efficiently and quite frankly they look awful, spoiling the classic lines of the Top Hat! Apart from trying to put the outboard prop as near as practical to the position of the inboard prop it replaces, there is a good reason for the positioning of the well, which can best be appreciated when driving through waves or when working on the foredeck with the stern hung outboard wanting to run in fresh air. I think you will find that it is not the hp of the motor that is important, rather than how far under the water the prop is rotating. Finally, I have a boarding ladder right where the stern bracket would go and we use it all the time to get on or off the boat. If you go back in General Discussion to my post on Jack LInes and look at the photo you will find it hard to see the outboard which is at the bottom of the guillotine which forms part of the pushpit. I have to say it looks neat and works a treat. The motor, when down is in the same position that it would have been when mouted on the permanent bracket. it just hoists up and down when needed and only comes out for service.

John S "Sombrero"
Sombrero
 
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Re: Outboard Motors......

Postby karl010203 » Sat Apr 17, 2010 9:02 am

Hey John - I have looked at your pic in the other photo and am really intrigued at the pushpit, a little hard to see the set up for your outboard, any chance you have photos looking astern...

I am unsure how you get your outboard from the bracket into the well - but it certainly looks like it is well set up - including the adjustable back stay.
karl010203
 
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Re: Outboard Motors......

Postby Shaun » Sat Apr 17, 2010 10:56 am

Gday Austin,

Night Cap has a 2009 Mercury 8hp LS 2-stroke, she used to have an Evinrude 6hp LS 2st, but i didnt trust the old motor 100%, but only because i dont know much about outboards.
The running-in process is a bit annoying for new outboards, but at least you know its been done.
Cruising at 1/2 to 3/4 throttle uses 2lt per hour, roughly 4 - 4.8kts.

Ive read 8hp 4 strokes can use as little as just under 1lt p.h.

The biggest bain is lifting it out of the well & onto a bracket on the pushpit.

TopHatSailing Mar2010 012.jpg
Outboard sitting on pushpit bracket
TopHatSailing Mar2010 012.jpg (51.86 KiB) Viewed 9835 times


Your fortunate with the cutout in the transom, enabling you to get the prop out of the water.

When i was reasearching to buy the new motor, i also liked the reputation of the Tohatsu, but i was told that all Mercury's under 15hp are made by Tohatsu, they certainly look identical, merc also included the hi-thrust prop(Tohey hi-thrust props were $200-ish extra), plus the merc's were $250-ish cheaper aswell.

The exhaust smoke is probably not an issue for you, with the cut-out??

For those of us with the outboard in the well, on the old Evinrude the exhaust port just under the cowling was blocked up with a bit of timber, seemed to be ok with no probs.
I was talking to Steve(diesel mechanic & HRYC member) at the Regatta, he suggested instead of blocking that exhaust port, to vent it outside the boat with plastic tubing - good idea! :idea:

If your going to keep the outboard always in-situ, the weight of the 4 stroke wouldn't be a prob,
some say 4 strokes vibrate more than 2 st, i dont know :?:

If your going to be pushing against tide, current or adverse weather i'd go for the 8hp(or more only if they come at same cost, weight, fuel economy of the 8hp), in a harbour or lake the 6hp would be fine.

cheers
Shaun
Camden Haven River,
Mid Nth Coast, NSW

Order of the Albatross - 2011
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Re: Outboard Motors......

Postby Sombrero » Sat Apr 17, 2010 11:03 pm

Hi Karl, thanks for your favourable comments. I am proud of the way my boat is set up and I spend a lot of time thinking of and making improvements. I purchased Sombrero with the outboard lowering system already in place. So I take no credit for the idea. When the wife comes back with the camera I will take some photos, but in the meantime I will give a verbal explanation. From my photo as seen by you, you will notice that the pushpit tubework has been added to to incorporate two tubes that run down to where the old outboard bracket was. A new timber bracket with stainless plates bolted to each side with SS tubing a size up on that used for the upright tubes welded to the plates enables the outbourd bracket to slide vertically up and down in and out of the well. I have a single pulley system for each side and holes drilled in the upright tubes to insert pins ( hanging from light line each side) when the motor is lifted clear of the water. Very little effort is required to lift the motor and it sits comfortably down in the well when running. The vertical posts have flat SS plates at the base which are bolted through the cockpit floor. The rest of the tubework is simply pop rivetted to the pushpit. There are two side braces and two running back to the pushpit itself. The tubework does not interfere with getting in or out of the boat, in fact it makes for a handy place to stand on while boarding.
Regards, John S "Sombrero"
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Re: Outboard Motors......

Postby ozzibod » Sun Apr 18, 2010 10:02 pm

G'day John S, Mark, Michael, Karl and Shaun,

Thank you so very much for all of your input. After your advice, I am now leaning towards a Mercury or Tohatsu either 2 stroke or 4 stroke with as long a shaft as I can get. I measured today the height above the waterline that my transom is, remembering that it is a cut-out version and it sits 17.5 inches above the waterline. I figure that I will need something in the long shaft department at least.
The cutout will accomodate a motor up to 12.5 inches wide at the point above where it clamps on to the transom although I could engage a small amount of controlled violence if required to widen the cutout if absolutely necessary, although I would rather not go down that path.
If I went for a 4stroke, I guess a 9.9hp would be the go as the engine block in the 4 strokes is the same for both the 8hp and the 9.9hp and therefore the weight also. Similary the 2 strokes in Tohatsu/Mercury have the same engine block between the 6hp and the 8hp.
My main dilemma now is: Am I to go for a lighter motor in the 2 stroke and put up with extra fuel consumption or do I go the heavier with the 4 stroke and get better cruising range. The other aspect which I haven't considered is the maintenance factor. Are 4 strokes more onerous for maintenance?
It seems from your posts that a 2stroke may be the answer in my case. A 2stroke that will do about 2 litres an hour at 1/2 to 3/4 throttle and doddling along at about 4-4.5 knots would be much better than what I have being an old 8hp 2stroke Evinrude that slurps about 4 litres an hour to do the same. Also enjoying the simplicity and low maintenance of the 2 stroke.

Once again, many thanks for your help. If you have anything else you would like to add, I will be all ears.

Cheerio for now
Austin
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